Satellite communications systems have been widely deployed over the past several decades. By way of example, Direct Broadcast Satellite (DBS) services have increasingly expanded to provide a variety of video program services directly to people's homes, apartments, and offices. In a conventional direct-to-home (DTH) satellite communication system, one or more telecommunications satellites in geosynchronous orbit receive media content from a broadcast “uplink” center. The satellite then radiates microwave signal beams to send the media content across a geographical region of the planet. For example, in the case of satellite service providers like DirectTV® video programs are broadcast across a wide region of the continental United States from several satellites in geosynchronous orbit above the Earth's equator.
Subscriber homes in the U.S. typically utilize an outdoor antenna dish mounted to their roof or an exterior wall to receive the satellite-transmitted signals. A satellite receiver or set-top box within the home is connected to the antenna for acquiring the satellite carrier signal and displaying the video program content received from the satellite transmission. As is well known, the satellite receiver may include decompression, decryption, decoder, demodulation and other circuitry for converting the received signals into a format (e.g., high definition television (HDTV), standard definition television (SDTV), etc.) suitable for viewing on a display device by the subscriber. For example, for direct-to-home digital satellite carriers which conform to Digital Video Broadcast (DVB) standards, the satellite receiver is configured to receive a set of parameters that may include the polarization, symbol rate, forward error correcting (FEC) rate and frequency to acquire the satellite digital carrier. U.S. Pat. Nos. 6,473,858, 6,430,233, 6,412,112, 6,323,909, 6,205,185, and 5,742,680 describe various conventional satellite communication systems that operate in this manner.
Satellite transmissions are often grouped in channel sets, wherein each channel set spans a certain transmit band. The channel sets are typically isolated by different electromagnetic polarizations. For instance, channel sets may be transmitted with linear polarization (i.e., horizontal or vertical) or circular polarization (i.e., left-hand or right-hand). These channel sets are detected on a polarization-sensitive antenna assembly through a low-noise block converter (LNB) mounted opposite a parabolic antenna dish. The LNB may be configured, for example, to detect the horizontal or vertical polarized signals reflected from the antenna dish. The LNB connects to the satellite receiver unit or set-top box located inside the subscriber's home via a coaxial cable.
In some receiving systems two LNBs are provided to receive both channel sets so that multiple television sets within a home may view different program channels simultaneously. Examples of different satellite data receiving systems are found in U.S. Pat. Nos. 6,424,817 and 5,959,592.
One of the problems with satellite communication systems is that they generally require an unobstructed line-of-sight between the orbiting satellite and the receiving antenna dish. In the United States, for instance, satellites typically orbit above the equator and are therefore “seen” by the antenna above the southern horizon. A home in a densely populated metropolitan region, however, may have its view of the southern sky obstructed by a tall building. In other cases, apartment dwellers living in units on the north side of a building may be precluded from mounting an antenna anywhere to receive satellite transmissions from a satellite orbiting above the southern horizon.
In other cases, landlords who own apartment buildings containing multiple units may be reluctant to permit tenants to mount multiple antenna dishes on their structure or route cable wires through the exterior and interior of the building. Routing of wires is also a problem in homes, particularly when multiple televisions are to receive programming services. The line-of-sight requirement and the problem of multi-dwelling units (MDUs) have therefore limited the number of homes that can receive digital services from satellite vendors.
An additional problem that satellite vendors generally face is the difficulty of providing interactive data services to their customers. Some specialized satellite service providers offer two-way data services, but these systems require the subscriber to purchase a fairly large antenna dish (e.g., 3-5 feet wide) with increased power demands for uplink transmission to the satellite. Another drawback is the inherent latency associated with signal transmission from Earth to the orbiting satellite, and then back down to Earth. This latency can produce sluggish system performance as compared to terrestrial cable systems, for example, when the user wants to access a web page containing large amounts of content and data.
Thus, there is a pressing need for new apparatus and methods for distributing satellite services and video content to the general population on an expanded basis. There is also a need for a communication network that provides additional services, such as interactive data services, to subscribers at a competitive cost and at a high performance level.